The present invention generally relates to improvements in cameras having self-contained interchangeable photographic objective lenses and it relates more particularly to an improved camera containing interchangeable objective lenses of different focal lengths for example, a pair of telephoto and standard objective lenses or a pair of telephoto and wide angle objective lenses.
Cameras have heretofore been available and proposed which are provided with a pair of photographic objective lenses built into and self-contained in the camera and which are selectively employed in photographing depending on the desired field of view.
Among these types of cameras are the slidable type in which there is provided a mounting plate slidable in a direction at a right angle to the photographing or picture taking optical axis and having two taking or photographic objective lenses mounted thereon in parallel relation to each other, and the so-called turret type in which there is provided a mounting disc supported on a pivot parallel to the picture taking optical axis with two or more taking lenses mounting thereon, whereby upon interchanging one lens with another, the mounting disc is rotated through a given angle to bring a desired taking lens into the picture taking optical path (the so-called turret type). However, these types of cameras pose a problem in that upon taking a picture, focusing must be separately adjusted for each of the taking lenses, because the two taking lenses are so designed as to be focused individually. For instance, when an object at a distance of 5 meters is to be photographed by using two or more interchangeable taking lenses so as to take two or more pictures, then one lens is focused upon the object for photographing, after which the lens is interchanged with the other lens, followed by the focusing of the new lens to the object distance of 5 meters. This results in a complicated and highly time consuming operation. Thus, in the case an object moves fast, a photographing opportunity is frequently missed.
In addition, with the aforesaid prior art cameras, as two taking lenses are mounted on a plate in the manner that the rearmost portion of each lens does not lie in the rear of the plate, when they are housed within a camera body, with the two lenses placed in parallel with a picture optical axis, the length of a camera body must be increased by a length of at least the additional length of the lens having the longer focal length (a telephoto lens in the case of a combination of a telephoto lens and a standard lens), thereby increasing the size of the camera body.
In addition, with the aforesaid prior art cameras, as the respective taking lenses are focused individually, it often occurs that either of the lenses are moved from its operative to its retracted or rest position with the lens being in a condition adjusted to a focus on an object at a short distance, i.e., in the condition where the lens is extended and of maximum increased length. As a result, a large space must be provided in the camera body for the accomodation of the lenses without shortening the extended lens.